JP2001093663A - Drive circuit of organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive circuit with a refreshing circuit for prolonging the service life of an organic electroluminescence element. SOLUTION: At least an anode 12 made of a transparent conductive material, an organic layer 13 consisting of at least one layer and a cathode 14 facing the anode 12 are mounted on a transparent substrate 11. The anode 12 is divided into plural segments Seg1 to Seg 7, corresponding to the shapes to be displayed, and the cathode 14 is set as a common Com. An organic electroluminescence element 10, which can emit light in a prescribed pattern, by connecting a DC power source Vcc between the segments Seg1 to Seg7 and the common Com and static driving. In addition, a power feeding circuit 30 for making the potential of thesegments Seg1 to Seg7 and the common Com reverse or same at a prescribed timing and a control circuit 40 for controlling the power feeding circuit 30 are mounted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a driving circuit for an organic electroluminescence element.

[0002]

2. Description of the Related Art As shown in FIG. 4, an anode 12 made of a transparent conductive material such as indium tin oxide (ITO) and an organic layer comprising at least one layer (at least a single organic light emitting layer) are provided on a transparent substrate 11. A layer structure or a multilayer structure in which any one of a hole injection layer, a hole transport layer, an electron transport layer, etc. is laminated with an organic light emitting layer from the anode side) 13 and a metal conductive material such as aluminum (Al). Cathode 14
EL device 1 having at least
0 is disclosed, for example, in Japanese Patent Publication No. 6-32307.

[0003] Such an organic electroluminescent device 1
Numeral 0 indicates that light can be emitted in a predetermined pattern depending on the shapes of the anode 12 and the cathode 14. By applying a DC voltage of several volts to several tens of volts between the anode 12 and the cathode 14, The light emission corresponding to the above pattern can be seen through the transparent substrate 11, and has an advantage that a low voltage drive by a DC power supply is possible as compared with a thin film type or dispersion type electroluminescence element.

One of the anode 12 and the cathode 14 is divided and formed as a plurality of display pixel electrodes (segments) corresponding to a display shape, and the other is used as a common electrode (common) by connecting a power supply between the two electrodes. A so-called segment type organic electroluminescent element for selectively emitting light is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-106888.
There is an advantage that a desired display shape is easily obtained. In FIG. 5, the anode 12 has segments Seg1 to Seg7, and the cathode 14 has common Com. Vcc is a DC power supply, 2
0 indicates power from the DC power supply Vcc in each segment Seg1 to Seg
7 is a switch circuit for supplying or stopping (turning on or off) the current from the constant current circuit 20 to each of the segments Seg1 to Seg7. The constant current circuit 20 includes the segments Seg1 to Seg7. Constant current sections 20a to 20 that individually set current values so that the difference in current density in each of the segments Seg1 to Seg7 falls within a certain range according to the area.
g, and the display selection switch circuit 21 includes switches 21a to 21g located between the constant current units 20a to 20g and the segments Seg1 to Seg7.

In the organic electroluminescent element 10, the common Com is connected to the external DC power supply Vcc by one wire.
A book and wiring electrodes are prepared by the number of segments Seg1 to Seg7, and the switch 2 provided in each segment Seg1 to Seg7.
A desired display can be realized by the power supply control by 1a to 21g.

The circuit configuration shown in FIG. 5 can be replaced with an equivalent circuit shown in FIG. That is, the organic electroluminescence element 10 and the constant current circuit 20 are composed of the bulk resistance RB, the leak resistance RL and the element capacitance C1, the anode 12 and the cathode 14 of the organic electroluminescence element 10.
, The wiring resistance R2 of the anode 12, the wiring resistance R3 of the cathode 14, and the wiring capacitance C2.

[0007]

In the organic electroluminescent element 10, the electric field (for the same direction) applied for a long time due to the capacitive factors of the element capacitance C1 and the wiring capacitance C2, particularly the element capacitance C1 shown in FIG. It is known that polarization due to current) occurs and the polarization is not restored, so that the light emission luminance of the organic electroluminescence element 10 is reduced and the life is shortened. A refresh (functional recovery) technique for prolonging the life of such a so-called static drive circuit has been considered.

For example, Japanese Patent Application Laid-Open No. 4-308687 (Prior Art 1) discloses a method in which a voltage (reverse voltage) in a direction opposite to a light emitting electric field is intermittently applied at intervals of 20 milliseconds or less. Japanese Patent Publication No. 1318 (Prior Art 2) discloses that a drive voltage and a reverse voltage or a zero voltage are alternately applied at a predetermined frequency. Although circuit configurations for applying a reverse voltage are disclosed, the prior art 1 may not be able to obtain a sufficient refresh effect due to the time constraint of 20 milliseconds or less. Since it is necessary to alternately apply a voltage and a reverse voltage or a zero voltage at a predetermined frequency, the driving method becomes complicated, and in the prior art document 3, the reverse voltage is applied in a short time so as not to recognize the flicker caused by the application of the reverse voltage. May not sufficient refresh effect can be obtained in some cases because of the need in the same manner as prior art 1 is located, both had to leave room for improvement in actual use.

The present invention has been made in view of such a problem, and can realize a refresh circuit for extending the life of the organic electroluminescence element 10 with a simple circuit configuration. It is intended to provide a driving circuit.

[0010]

According to a first aspect of the present invention, there is provided a driving circuit for an organic electroluminescence device, comprising: an anode made of a transparent conductive material on a transparent substrate; A cathode made of a metal conductive material so as to face the layer and the anode, one of the anode or the cathode is divided into a plurality of segments corresponding to a shape to be displayed, and the other is made common, and the other is made common. And a DC power supply connected between the power supply and the common, and a display is performed in a predetermined pattern by light emission at the segment where the drive voltage is applied at the time of lighting when a drive voltage is applied based on the DC power supply. A luminescence element, wherein the drive voltage and the organic electroluminescent element are applied to the segment in a non-lighting state where the drive voltage is not applied. And a power supply circuit for applying a characteristic recovery voltage for neutralizing internal polarization of Nesensu element, provided a control circuit for controlling the same.

According to a second aspect of the present invention, at least an anode made of a transparent conductive material on a transparent substrate, an organic layer composed of one or more layers, and a cathode made of a metal conductive material opposed to the anode are provided. Having a direct current power supply connected between the segment and the common while dividing and forming one of the anode and the cathode into a plurality of segments corresponding to the shape to be displayed and the other as a common. An organic electroluminescent element which performs display in a predetermined pattern by light emission at the segment where the drive voltage is applied at the time of lighting when a drive voltage is applied based on a power supply, wherein the drive voltage and the drive voltage are not applied The characteristic of the driving voltage for neutralizing the internal polarization of the organic electroluminescent element to the segment at the time of non-lighting is opposite to that of the driving voltage. And a power supply circuit for applying a performance recovery voltage is pressure, providing a control circuit for controlling the same.

According to a third aspect of the present invention, there is provided at least an anode made of a transparent conductive material on a transparent substrate, an organic layer composed of at least one layer, and a cathode made of a metal conductive material opposed to the anode. Having a direct current power supply connected between the segment and the common while dividing and forming one of the anode and the cathode into a plurality of segments corresponding to the shape to be displayed and the other as a common. An organic electroluminescent element which performs display in a predetermined pattern by light emission at the segment where the drive voltage is applied at the time of lighting when a drive voltage is applied based on a power supply, wherein the drive voltage and the drive voltage are not applied A characteristic of being a zero potential voltage for neutralizing the internal polarization of the organic electroluminescent element to the segment when not lit And a power supply circuit for applying a recovery voltage, providing a control circuit for controlling the same.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the timing of applying the characteristic recovery voltage is determined based on the segment having the least non-lighting time as a reference. The control circuit controls the number of times or the time to be short.

According to a fifth aspect, in the first to third aspects, the segment is the anode and the common is the cathode.

According to a sixth aspect of the present invention, in the first to third aspects, the segments are divided into seven and are arranged in the shape of a sun, and a numeral " A power supply circuit for applying the driving voltage so as to display “0” to “9” by light emission.

According to a seventh aspect, in the sixth aspect, the organic electroluminescence element is used as an odometer or a trip meter of a vehicle.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the structure of the first aspect,
It has a DC power supply Vcc connected between the segments Seg1 to Seg7 and the common Com, and emits light by the segments Seg1 to Seg7 where the drive voltage is applied at the time of lighting when a drive voltage is applied based on the DC power supply Vcc. An organic electroluminescent element 10 for performing display in a predetermined pattern for neutralizing the internal polarization of the organic electroluminescent element 10 to segments Seg1 to Seg7 in a non-lighting period in which a drive voltage and a drive voltage are not applied. By providing the power supply circuit 30 for applying the characteristic recovery voltage and the control circuit 40 for controlling the same, the life of the organic electroluminescent element 10 can be extended.

According to the second aspect of the present invention, there is provided a lighting device having a DC power supply Vcc connected between the segments Seg1 to Seg7 and the common Com, and a drive voltage being applied based on the DC power supply Vcc. An organic electroluminescence element 10 that performs display in a predetermined pattern by light emission at seven segments Seg1 to Seg7 to which the drive voltage is applied, and the drive voltage and the segments Seg1 to Seg7 at the time of non-lighting where no drive voltage is applied A power supply circuit 30 for applying a characteristic recovery voltage, which is a voltage having a characteristic opposite to the drive voltage for neutralizing the internal polarization of the organic electroluminescent element 10, and a control circuit 40 for controlling the same. By providing the organic electroluminescent element 10
Life can be extended.

According to the third aspect of the present invention, there is provided a lighting device having a DC power supply Vcc connected between the segments Seg1 to Seg7 and the common Com, to which a driving voltage is applied based on the DC power supply Vcc. An organic electroluminescence element 10 that performs display in a predetermined pattern by light emission at seven segments Seg1 to Seg7 to which the drive voltage is applied, and the drive voltage and the segments Seg1 to Seg7 at the time of non-lighting where no drive voltage is applied Power supply circuit 30 for applying a characteristic recovery voltage which is a zero potential voltage for neutralizing the internal polarization of the organic electroluminescence element 10
And a control circuit 40 for controlling the same, the life of the organic electroluminescent element 10 can be extended.

In addition, according to the configuration of the fourth aspect, the timing of applying the characteristic recovery voltage is determined based on the segments Seg1 to Seg7 that have the least non-lighting times as a reference, and a small number of times for the other segments Seg1 to Seg7. By using the control circuit 40 for controlling so as to have a short time, the characteristic recovery voltage applied during non-lighting is also applied at a constant cycle.
Internal polarization in each of the zero segments Seg1 to Seg7 can be substantially uniformly neutralized.

According to the configuration of the fifth aspect, the segments Seg1 to Seg7 are the anode 12 and the common Com is the cathode 1.
When the number is 4, the segments Seg1 to Seg7 can be formed in an arbitrary shape by the anode 12 for which pattern formation is easy, and desired light emission can be obtained.

According to the configuration of the sixth aspect, the segments Seg1 to Seg7 are divided into seven segments and arranged in the shape of the sun, and the number “0” is set at the seven segments Seg1 to Seg at the time of lighting. The power supply circuit 30 that applies a drive voltage so as to display “9” by light emission from the power supply circuit 30 has a high possibility that lighting and non-lighting will be repeated at a fixed rate, and the characteristic recovery applied during non-lighting will be high. The voltage is also applied at a constant period, so that the internal polarization of the organic electroluminescence element can be substantially uniformly neutralized.

According to the configuration of the seventh aspect, the organic electroluminescent element 10 is used as an odometer or a trip meter of a vehicle, so that each digit of the traveling distance is a number “0” to “9”. Always occur at a constant cycle, the characteristic recovery voltage applied during non-lighting is also applied at a constant cycle, and the internal polarization of the organic electroluminescence element 10 can be neutralized.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the embodiments shown in the accompanying drawings, in which the same or corresponding parts as those in the prior art are denoted by the same reference numerals.

FIG. 1 shows the shapes of the anode 12 and the cathode 14. In this embodiment, the anode 12 is divided into a plurality of segments, and the cathode 14 is used as a common common to selectively emit light. The organic electroluminescent element 10 is a so-called segment type display capable of displaying “0” to “9”. To be more specific, the anode 12 is configured in the shape of a day, which is composed of a total of seven segments, six segments Seg1 to Seg6 sequentially located clockwise from the top and one segment Seg7 located at the center. ing.

As shown in FIG. 2, each of the segments Seg1 to Seg7 includes a power supply circuit 30 connected to a DC power supply Vcc.
Are individually connected to the respective supply units 30a to 30g, and the respective supply units 30a to 30g configuring the power supply circuit 30
Is connected to a control circuit 40, which will be described later, so as to control power supply to each of the segments Seg1 to Seg7.

The cathode 14 is a single common Com having a shape facing the anode 12, and is electrically connected to the ground as shown in FIG.

Next, the operation of the circuit shown in FIG.
This will be described with reference to the timing chart of FIG.

When light emission is performed at one segment Seg, a drive voltage necessary for light emission is applied from the supply unit 30a. The same applies to the segments Seg2 to Seg7. Accordingly, when the numbers “0” to “9” are displayed by the light emission of the segments Seg1 to Seg7, the control circuit 40 controls the respective supply units 3 of the power supply circuit 30 to perform the light emission shown in FIG.
0a to 30g are controlled.

By the way, the segments Seg1 to Seg7 do not always emit light (is not driven) due to any of the numbers “0” to “9” (when not lit). For example, the segment Se
g1 is not driven in the case of the numbers “1”, “4”, and “6”, and is not lit.

In the present invention, at the time of such non-lighting, the control circuit 40 applies a characteristic recovery voltage consisting of a voltage (reverse voltage) having a characteristic opposite to the drive voltage or a voltage of zero potential (zero voltage) to the segments Seg1 to Seg1. Supply unit 30 so as to apply to Seg 7
a to 30 g are controlled.

For example, in the case of the number "1", the supply section 30a and the supply sections 30d to 30g apply the characteristic restoring voltage to the segments Seg1 and Seg4 to Seg7 in the non-lighting state. Segment Se that is lit
The control unit 40 controls the g2 and Seg3 to apply a drive voltage from the supply units 30b and 30c.

As a result, the anode 12 and the cathode 14 of the organic electroluminescent element 10 have opposite potentials or the same potential at any time, and the inside of the organic electroluminescent element 10 is affected by the element capacitance C1. Since the accumulated charges are discharged, the polarization can be recovered by this, and the organic electroluminescent element 1
0 life can be extended.

The segments Seg1 to Seg7 vary in the number of times of non-lighting. The number of times of non-lighting is the largest in segment Seg5, and the smallest is 1 in segment Seg3. Times. Therefore, the timing of applying the characteristic recovery voltage is set to the segment Seg.
By controlling the control circuit 40 such that the number of times or the time is short in the segment Seg5 with reference to 3,
The characteristic recovery voltage applied at the time of non-lighting is also applied at a constant cycle, and the internal polarization in each of the segments Seg1 to Seg7 of the organic electroluminescent element 10 can be substantially uniformly neutralized, and the characteristic recovery can be performed. It is not always necessary to apply the operating voltage during non-lighting.

As described above, each of the supply units 30a to 30g of the power supply circuit 30 and the control circuit 40 exhibit a function of a refresh circuit for neutralizing (cancelling) the internal polarization of the organic electroluminescence element 10, and The life of the electroluminescent element 10 can be extended, and a sufficient refresh effect can be obtained without affecting the light emitting display by using the non-lighting time of the segments Seg1 to Seg7.

In this embodiment, seven segments Se are used.
Although the example in which g1 to Seg7 are arranged in the shape of a day and the numbers “0” to “9” are displayed by light emission is shown, a plurality of segments are displayed.
It goes without saying that the present invention can be applied to a case where any design such as a character or a symbol is displayed by light emission using Seg1 to Segn (n is an arbitrary integer of 2 or more).

In particular, as in the above-described embodiment, the seven segments Seg1 to Seg7 are arranged in the shape of a date and the numbers “0” to
If the lighting and non-lighting in which "9" is displayed by light emission are repeated at a constant rate, the characteristic recovery voltage applied at the time of non-lighting will also be applied at a constant cycle, and the organic It is suitable for neutralizing the internal polarization of the electroluminescence element 10.

The seven segments Seg1 to Seg7
Are arranged in parallel, the organic electroluminescent element 10 can be used as, for example, an odometer or a trip meter of a vehicle. In this case, each digit of the traveling distance is a number “0” to Since “9” always occurs at a constant cycle, the characteristic recovery voltage applied at the time of non-lighting is also applied at a constant cycle, and the internal polarization of the organic electroluminescence element 10 can be neutralized. it can.

The segments Seg1 to Seg7 are connected to the anode 1
2. Com was formed with cathode 14, but conversely, segment S
eg1 to Seg7 may be formed by the cathode 14, and Com may be formed by the anode 12. However, since it is generally easier to pattern the anode 12, it is desirable in the manufacturing process to form the segments Seg1 to Seg7 with the anode 12 and Com with the cathode 14.

[0040]

As described above, according to the present invention, by applying a characteristic recovery voltage for neutralizing (cancelling) the internal polarization of the organic electroluminescence element, the life of the organic electroluminescence element can be extended. Can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an electrode shape according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of the embodiment.

FIG. 3 is a timing chart in the above circuit.

FIG. 4 is a cross-sectional view of a main part of the organic electroluminescence element.

FIG. 5 is a circuit diagram of a conventional technique.

FIG. 6 is an equivalent circuit diagram of the above circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Organic electroluminescent element 12 Anode 14 Cathode 30 Power supply circuit 30a-30g Supply part 40 Control circuit Vcc DC power supply Seg1-Seg7 Segment Com common

Claims (7)

[Claims] 1. An anode comprising a transparent conductive material on a transparent substrate, an organic layer comprising at least one layer, and a cathode comprising a metal conductive material facing the anode, wherein the anode or the cathode is provided. A DC power supply connected between the segment and the common, and a driving voltage is applied based on the DC power supply. An organic electroluminescent element that performs display in a predetermined pattern by light emission at the segment location to which the drive voltage is applied when the drive voltage is applied, wherein the drive voltage and the segment when the drive voltage is not applied and the drive voltage is not applied to the segment. A power supply circuit for applying a characteristic recovery voltage for neutralizing the internal polarization of the organic electroluminescence element, and A driving circuit for an organic electroluminescence element, comprising: a control circuit for controlling the driving circuit. 2. An anode comprising a transparent conductive material on a transparent substrate, an organic layer comprising at least one layer, and a cathode comprising a metal conductive material facing the anode, wherein the anode or the cathode is provided. A DC power supply connected between the segment and the common, and a driving voltage is applied based on the DC power supply. An organic electroluminescent element that performs display in a predetermined pattern by light emission at the segment portion to which the driving voltage is applied when the driving voltage is applied, wherein the driving voltage and the segment at the time of non-lighting when the driving voltage is not applied to the segment. A characteristic recovery voltage which is a voltage having a characteristic opposite to the driving voltage for neutralizing the internal polarization of the organic electroluminescence element. A driving circuit for an organic electroluminescence element, comprising: a power supply circuit for applying voltage; and a control circuit for controlling the power supply circuit. 3. An anode comprising a transparent conductive material on a transparent substrate, an organic layer comprising at least one layer, and a cathode comprising a metal conductive material facing the anode, wherein the anode or the cathode is provided. A DC power supply connected between the segment and the common, and a driving voltage is applied based on the DC power supply. An organic electroluminescent element that performs display in a predetermined pattern by light emission at the segment portion to which the driving voltage is applied when the driving voltage is applied, wherein the driving voltage and the segment at the time of non-lighting when the driving voltage is not applied to the segment. A power supply for applying a characteristic restoring voltage which is a zero potential voltage for neutralizing the internal polarization of the organic electroluminescence element. A driving circuit for an organic electroluminescence element, comprising a supply circuit and a control circuit for controlling the supply circuit. 4. The control circuit according to claim 1, wherein a timing of applying the characteristic recovery voltage is controlled based on the segment having the least non-lighting time as a reference, so that the other segment has a smaller number of times or a shorter time. The driving circuit for an organic electroluminescence element according to claim 1, wherein 5. The driving circuit for an organic electroluminescence element according to claim 1, wherein the segment is the anode and the common is the cathode. 6. The driving voltage is set so that the segments are divided into seven and arranged in the shape of the sun, and the numbers “0” to “9” are displayed by light emission at the segment locations at the time of lighting. 4. The driving circuit for an organic electroluminescence element according to claim 1, wherein the driving circuit is a power supply circuit for applying the voltage. 7. The driving circuit for an organic electroluminescence element according to claim 6, wherein the organic electroluminescence element is used as an odometer or a trip meter of a vehicle.